1. Field of the Invention
The invention in general relates to steam turbines, and more particularly, to a conductivity sensor array for monitoring purposes.
2. Description of the Prior Art
It is well known that the impurities in steam used to drive steam turbines are a corrosive concern and that deposition of corrosive salt impurities on the rotating turbine blades may lead to stress corrosion cracking failure.
Of particular concern is sodium chloride which, although dissolved in the superheated steam at low concentrations, can deposit at high concentrations as the steam expands through the turbine. Near the exit of the low pressure section of the turbine arrangement, the steam undergoes an expansion whereby a consequent transition from a dry to a wet condition takes place. The entrained sodium chloride could then form a saturated solution which could lead to corrosion and cracking of the rotating blades.
If the location of the salt deposition zone is known, the expansion path of the steam can be modified such that the salt solution deposition can be shifted to a stationary turbine blade. An arrangement for detecting and shifting the zone is described and claimed in U.S. Pat. No. 4,386,498.
The present invention provides for an arrangement by which it is possible to more accurately determine the exact location of the salt solution zone as well as its direction of movement, so as to more accurately deposit the salt solution zone on a stationary turbine blade by manipulation of turbine operating parameters.